The present invention concerns in general an improved patient support, and in particular concerns supports having an improved stretchable covering and concerns improved wheelchair cushions of particular construction.
Decubitus ulcers, also known as bed sores, are a well-known and widespread problem and significant concern for bed-ridden patients or others who are constrained to prolonged periods of relative nonmovement, such as wheelchair patients. Pressure sores can begin to form due to prolonged or excessive pressure on the tissue, such as due to natural bony projections or prominences, which results in occlusion or blockage of capillary blood flow.
One common approach to addressing the foregoing concerns for patients having various stages or degrees of immobility is to provide pressure relief. Many typical approaches to pressure relief involve the use of resilient foamed materials formed for providing various specific patient support surfaces designed to alleviate or reduce tissue pressures.
One example of a specialized foam body support is shown by Spann (U.S. Pat. No. 4,573,456). FIGS. 1 through 3 illustrate a specialized resilient foam support for receiving the limb of an orthopedic patient. FIG. 4 of such '456 patent illustrates a rectangular generally flat block of synthetic foam with slits formed at right angles in an upper surface so as to form cubicle support members between intersecting rows of slits. Air channels are further provided at the base of the slits to conduct heat and moisture away from the patient for further enhanced prevention or treatment of pressure sores. The foam of such constructions would typically have a density of about 1.4 to about 1.8 pounds per cubic foot and a 25 percent indentation load deflection rating of about 44 pounds.
While the foregoing efforts have been effective to a degree, further improvement has been sought. For example, many relatively immobile patients also suffer from occasional, or even frequent, incontinence problems. For hygienic purposes, it is generally desirable that any foam support material be shielded from moisture, such as in the event of involuntary discharges of bodily fluids by a patient. For example, Landwirth (U.S. Pat. No. 3,284,817) discloses a waterproof sheath layer 20, formed such as from polyvinyl chloride, and heat sealed about a foam cushioned body 10. A further outer sheath is provided removably mounted and formed of a fabric material for washing. The removable cover is designed to fit snugly around the inner sheath.
One difficulty which in general may be encountered with coverings over segmented foam surfaces is referred to as the hammocking effect. During the hammocking effect, the advantages of the segmented support surface are lost, to varying degrees, because the covering itself tends to counter or defeat the independent movement of the support segments. Separately covering the independent segments would be one approach, but involves greater expense and can reduce the overall hygiene if personnel are not properly instructed in cleaning crevices between respective segments.
Other seat arrangements seek to improve body support by forming grooves of a certain depth in the face of a polyurethane foamed support, such as in hexagonal shapes or the like. Examples of such constructions are found in Stalter (U.S. Pat. No. 4,265,484); Burkholder et al. (U.S. Pat. No. 4,092,751); and Stalter et al. (U.S. Pat. No. 4,073,020). In the above-noted references, the hexagonal or other grooves are formed directly in the overall body support. In many instances of patient specific settings, the patient support provided for pressure relief is an added features to an existing device, such as a chair or wheelchair. Accordingly, any excessive thickness of the pressure relief support, for example, such as a cushion for a wheelchair, can create or add to difficulty of a patient getting into or out from the wheelchair.
The above-noted hammocking effect can also occur not only in specific pressure relief support devices such as wheelchair cushions, but can also be prevalent in the case of mattress pads or the like where a covering is to be utilized. Such can be the case in a wide variety of various segmented mattress pad surfaces, if improperly used with various coverings. Examples of prior art mattress pads with upper support surfaces having independent segments or otherwise independently movable projections are disclosed in:
______________________________________ U.S. Pat. No. INVENTOR ______________________________________ 5,025,519 SPANN ET AL. 5,007,124 RABURN ET AL. 4,901,387 LUKE 4,862,538 SPANN ET AL. 4,686,725 MITCHELL DES. 322,907 RABURN DES. 307,690 RABURN DES. 307,689 SCHAEFER DES. 307,688 SCHAEFER DES. 307,687 RABURN ______________________________________
In addition, other prior devices, such as head and neck pillows may make use of segmented support surfaces which would also be subject to the hammocking effect if improperly utilized with certain coverings. One example of a foam pillow construction for head and neck support is shown by Schaefer et al. (U.S. Pat. No. 4,726,087).
The disclosures of the above-referenced U.S. patents are fully incorporated herein by reference.